In the west, the comet appeared from a crystal-blue sky over the Hyatt Regency Hotel. In the east, the soon-to-be-eclipsed full moon, reddish Mars riding above it, rose over the Rusty Scupper restaurant.

And peering at the sky through a forest of streetlights were hundreds of people celebrating what promised to be one of the great evenings in the history of urban astronomy, until clouds rolled in to eclipse the eclipse.

It was a night for amateurs, the folks who ordinarily wouldn't know Hale-Bopp from be-bop and are a little hazy on how a light-year is different from a regular year.

People such as Mary Pat Melito, a Revco pharmacist from Towson who "can pick out Orion on a good night," but who seemed to win the unofficial honor of First Comet Spotter.

"I think that's it! Straight above the second bump on that building! Across from that tower! The fuzzy thing!" cried Melito, 40, as people craned their necks and shaded their eyes and picked it out in the darkening sky.

A police helicopter rumbled past, its occupants looking earthward, their minds on less celestial developments.

For a couple of blessed hours, before the weather taught the beginners how frustrating a hobby astronomy can be, it was a festival of astronomical proportions on the plaza in front of the Maryland Science Center, as the crowd peaked with more than 300 people in line for a look through a dozen telescopes provided by the center and volunteers from the Baltimore Astronomical Society.

Families drove in from the suburbs -- reversing the advice usually given to those who want to see the stars. Couples decided to take in the sky instead of a movie. Conventioneers, Harborplace diners and even a high school lacrosse team from upstate New York meandered past, stopped to find out what the fuss was about and stayed to gaze.

"This is as big a nighttime crowd as I can remember," said Jim O'Leary, director of the center's Davis Planetarium and unofficial master of ceremonies at many nights of skywatching.

As his son, Brendan, 13, handed out star charts, O'Leary held aloft a softball and explained that, if Hale-Bopp were that size, its tail would reach to Boston. Actually, at 25 miles across, its icy core is about the size of metropolitan Baltimore, and its vaporous tail may be 100 million miles long, he said.

The crowds were lured by the coincidence of last night's almost-total lunar eclipse -- behind those clouds at 11: 40 p.m., 92 percent of the moon was darkened by the earth's shadow -- with one of the few comets in this century bright enough to be visible even amid city lights.

Jerry Burchett had given his wife, Dawn, a small telescope for Christmas in 1995. She hadn't used it much -- mostly just to look at craters of the moon in front of their house in Waverly, standing in the middle of Homestead Street with Jerry watching out for cars.

But last night Dawn Burchett, 42, skipped church -- "and it's revival week" -- and drove downtown to train her telescope on the comet.

By 7: 30, she had been transformed into an expert, as 50 people stood in line to share her scope and peppered her with science questions.

Jerry stood next to her with a pair of binoculars, revealing to a smaller line the greatest secret of amateur astronomy: that you can spot things more easily with binocs and see them almost as well as with a telescope.

Mary Therese Hewins hefted her squirming 4-year-old son, Robert, to the eyepiece of the Burchett scope until he squealed and proclaimed, "It's a shooting star!" Then he trotted off to the harbor's edge with his sister, Laura, 7.

Their father, Dan Hewins, 43, teaches physics and chemistry at High Point High School in Prince George's County. He first spotted the comet on a 4: 30 a.m. jog two weeks ago and has used it to introduce his students to the wonders of astronomy.

"It's terrific timing because we just finished studying Kepler's PTC Laws," which govern the elliptical orbits of bodies around the sun, Hewins said.

For his students, whose world usually does not extend much beyond their favorite fast-food hangouts, astronomy offers a different perspective.

"I try to impress the kids -- 2,000 miles in our lives is a long way. Thirty million miles is incomprehensible to us. But in space, that's nothing," he said.

Gazing at the night sky, Hewins said, is a pleasant contrast with plenty of popular entertainment.

"It's one of the last things," he said, "that's free, wholesome and healthy."